The present invention relates to an electro-pneumatic device. It finds particular application in conjunction with controlling the electro-pneumatic device and will be described with particular reference thereto. It will be appreciated, however, that the invention is also amenable to other applications.
Conventional electro-pneumatic valves are driven by a controller in an open-loop manner. In open-loop designs, the controller relies on other system state variables to gauge whether the valve is functioning correctly. Signals from the other system state variables take time to reach the controller. Therefore, if the valve malfunctions, a delay exists between the time the malfunction occurs and the time the malfunction is detected by the controller. In safety-critical applications, the time delay may be too long for the controller to mitigate the effects of the malfunctioning valve. For example, if the valve malfunction results in too much braking pressure being applied, the time delay in conventional open-loop electro-pneumatic valves before the controller detects and mitigates the malfunctioning valve may be unacceptably long.
The present invention provides a new and improved apparatus and method which addresses the above-referenced problems.